Switching and modulation system



A. S. MAEDER SWITCHING AND MODULATION SYSTEM Original Filed Oct. 1, 1946 FIG. I

June 21, 1949.

I I! r 4 a A A v a I v w v In! BY LAURETTA MAEDER MU Patented June 21, 1949 SWITCHING AND MODULATION SYSTEM Abbott S. Maeder, deceased, late of East Hempstead, N. Y., by Lauretta Maeder Murphy, administratrix, East Hempstead, N. Y., assignor to The Sperry Corporation, a corporation of Delawar 8 Original application April 4, 1941, Serial No.

386,766, now Patent No. 2,408,425, dated October 1, 1946. Divided and this application August 3, 1944, Serial No. 547,862

4 Claims. 1

This invention relates to switching and modulating systems and more particularly to methods of and apparatus for varying the flow of electromagnetic energy from a source to one or more load circuits. This application is a division of application Serial No. 386,766, filed April 4, 1941, now Patent No. 2,408,425.

The principal object of the present invention is to provide a resonator as a coupler between a high frequency oscillator and a load circuit, together with means for shifting the natural frequency of the resonator from the frequency of the source, so as to selectively or periodically suppress the flow of energy from the source to the load circuit.

Other objects and advantages will become apparent from the specification taken in connection with the accompanying drawing showing a typical embodiment of the invention.

In the drawing,

Fig. 1 is a diagrammatic view showing the use of resonators interposed between an ultra high frequency oscillator and a pair of radiators, together with detuning means for suppressing the outputs of the respective radiators;

Fig. 2 is an enlarged sectional view through one of the resonators disclosed in Fig. l, illustrating mechanical tuning means for varying the natural period of the resonators.

Generally speaking, the invention comprehends interposlng a cavity resonator, normally tuned to the frequency of the generated waves, in the transmission line connecting the energy source with one or more load circuits. By periodically moving a tuning member within the cavity, the natural frequency of the resonator is varied, producing a variation in the flow of energy from the source to the resonator.

The source of high frequency energy is herein disclosed as a velocity modulation oscillator and amplifier I l of the type described in R. H. Varian Patent 2,242,275, dated May 20, 1941. The source preferably comprises one or more buffer amplifier stages, in order to stabilize the output frequency under varying load conditions.

Energy at constant frequency may be derived from the source ll through a. transmission line H, herein disclosed as a concentric cable. The energy may be divided and conducted along branch lines I3 and It to cavity resonators I5, each of which is provided with an input coupling device l6 for transferring energy from the line to the resonator. Energy may be tapped from the cavity and caused to flow along transmission lines I! and i9, respectively, as by an output coupling device I] within each resonator.

The resonators ii are of conventional design and may comprise a generally cylindrical outer casing formed of side walls 2| and end walls 22. Reentrant portion 23 extends as shown from one of the end walls part way to the opposite end wall, the reentrant portion being capped at its extremity to provide a completely enclosed chamber.

As is well known, the natural frequency of a cavity resonator may be altered by changin the size, shape or electrical characteristics of the chamber. By locating a movable tuning member 24 in the space between the end of the reentrant portion and the opposite wall 22, the frequency of the resonator may be altered according to the change in the electrical characteristics of the resonator resulting from the presence of the tuning member. If the tuning member is moved so as to vary the capacity between the end of the reentrant portion and the opposite wall, the frequency of the resonator correspondingly may be changed. Any type of movement, whether reciprocating, oscillating or rotary, may be employed, though for convenience in illustration, use herein is made of a disc-like member 24 mounted eccentrically on the shaft 25 of a. motor 26 for rotation of the member Within the chamber. The member 24 may be or any desired shape and may be oriented in any desirable manner relative to the chamber such that it recurrently alters the natural period of the resonator as it moves or rotates.

Assuming the member 24 to be in a given initial osition and the resonator IE to be resonant to the oscillations generated by the source ll, energy will flow freely between the input and output coupling devices l6 and II for transmission to a suitable load circuit. As the member 24 moves from its initial position, the resonator is detuned, reducing the flow of energy from the source to the resonator. If the frequency shift is sufficiently large, the flow of energy may be substantially terminated, so that the device may operate in the manner of a switch.

Fig. 1 discloses a pair of resonators l5 controlling the flow of energy to a pair of load circuits 21 and 28. The load circuits may be of any convenient design capable of utilizing the energy conducted along transmission lines l8 and I9, which circuits are herein shown, for purposes of illustration, as horn-type radiators of electromagnetic energy. It will be apparent that by properly synchronizing the motion of the tuning members in the resonators IS, the distribution of the energy to circuits 2i and 29 maybe coordinated in any desired fashion. Thus. by having the members It displaced from one another by an amount corresponding to one-halt oi a switching cycle, energy may be made to flow from the source ll first to load circuit 21 and then to load circuit 2|, recurrentiy. Although any conventional interlocking arrangement might be provided, it the two motors 20 comprise synchronous motors excited from the same source, the respective members ll operate in synchronism. It a single motor is employed to positively drive both mem' bers 24, a predetermined phase relationship may be maintained at all times between the members.

when employing a rotatable member 24, recurrent detuning is eifected by providing a periphery with successive portions located at progressively varying distances from the axis of rotation. e. g. the axis of shaft 25. The amount of frequency change is determined in part by the range over which the effective radius of the member 24 varies, it being possible to control the percentage of modulation of the radio frequency energy by proper design of the member 2|. Thus, also it is possible to audio-modulate the energy from source li according to the rate at which the member 24 alters the electrical characteristics of the resonator it. However, the desired audio modulation otherwise may be produced at the source il, as described in the parent application, and the respective resonators I! may be employed merely tor switching purposes.

The application of a tuning member to a cavity resonator provides distinct advantages over tuning members used with transmission lines. condults and the like, since cavity resonators ordinarily possess a much larger iigure of merit (high Q) as indicated by the ratio of reactance to resistance. For this reason, a large detuning eflect is obtained with relatively small mechanical movement and for a given detuning action, the mechanical mechanism may be of very small proportions, as compared with tuning mechanisms used with lower Q circuits.

As many changes could be made in the above construction and many apparently widely difler-' ent embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is: a

1. A cavity resonator comprising a substantially enclosed chamber, coupling means for connecting said chamber with a source of radio frequency energy and with an output circuit, respectively, means for reeurrently detuning said resonator and substantially completely halting the flow of energy from said source to said circuit comprising a rotatable member having at least a portion thereof projecting within said chamber, the extent of said projection remaining constant with rotation, and means for rotating said member so as to vary the position of said member within saidchamber and accordingly to vary the impedance of said resonator with respect to said source.

2. A cavity resonator comprising a substantially enclosed chamber having side walls, end walls, and a reentrant portion extending from one of said end walls partway toward the opposite end wall, a movable tuning member, said member comprising a rotatable disc-like element havin a periphery formed of successive portions whose distance from the axis of rotation varies progresslvely through a predetermined range, and means for continuously rotating said element so that said periphery progressively varies the space between said reentrant portion and said opposite end wall during recurrent cycles, thereby periodically varying the natural frequency of said cnamber.

3. A switching device for electromagnetic energy flowing from a radio frequency energy source to a load circuit, comprising a reentrant cavity resonator having end and side walls tunable to the frequency of said source, said resonator having input and output coupling means extending to said source and said load circuit. respectively, and periodically rotatable means within said resonator having portions of diflerent radius cooperative with said reentrant portion of said cavity to vary the natural frequency of said resonator.

4. An ultra high frequency transmission system comprising, means providing ultra high frequency energy of a predtermlned frequency, an ultra high frequency energy utilization device, a cavity resonator, ultra high frequency energy conduit coupling said energy providing means and said cavity resonator and said utilization device, said resonator including a cylindrical conductive casing with conductive end walls and a reentrant extension from one end wall toward the other end wall to form a gap therewith, movable means projecting within the gap between said reentrant extension and said other end wall in said cavity resonator, and means for recurrently varying the extension of said movable means in the gap, said resonator being tuned to said predetermined frequency when said movable means occupies a predetermined position in its range of movement.

LAUREITA MAEDER MURPHY, Administrfltria: of the Estate 0) Abbott S. Maeder,

Deceased.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,106,776 Trevor Feb. 1, 1938 2,142,630 Conklin Jan. 3, 1939 2,197,124 Conklin Apr. 16, 1940 2,198,025 Davies Apr. 23, 1940 2,227,372 Webster Dec. 31, 1940 2,241,937 Trevor May 13, 1941 2,241,976 Blewett May 13, 1941 2,244,756 Alford June 10, 1941 2,247,783 Massolle July 1, 1941 2,266,500 Lindenblad Dec. 16, 1941 2,301,163 Koch Nov. 3, 1942 2,402,663 Ohl June 25, 1946 

